求教关于dojo布局控件StackContainer的问题

请各位大大给我看看 我这代码哪错了 导致控件不能正常显示
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk2312">
<title>StackContainer</title>
<link rel="stylesheet" type="text/css" href="http://o.aolcdn.com/dojo/1.1/dijit/themes/tundra/tundra.css"/>
<link rel="stylesheet" type="text/css" href="http://o.aolcdn.com/dojo/1.1/dojo/resources/dojo.css"/>
    <script type="text/javascript" src="http://o.aolcdn.com/dojo/1.1/dojo/dojo.xd.js" djConfig="parseOnLoad:true" ></script>

        <script type="text/javascript">         dojo.require("dijit.layout.StackContainer");
            dojo.require("dijit.layout.ContentPane");
dojo.require("dojo.parser");
dojo.require("dojo.form.Button");
        </script>
</head>
<body class="tundra">

  <div id="stack" dojoType="dijit.layout.StackContainer" style="width:100px;height:100px;margin:5px;border:solid 1px">
       <div dojoType="dijit.layout.ContentPane">one fish..</div>
<div dojoType="dijit.layout.ContentPane">two fish..</div>
<div dojoType="dijit.layout.ContentPane">three fish..</div>
  </div>
  
  <button dojoType="dijit.form.Button" >&lt;
      <script type="dojo/method" event="onClick" args="evt">
dijit.byId("stack").back();
      </script>
  </button>
  
  <button dojoType="dijit.form.Button" >&gt;
      <script type="dojo/method" event="onClick" args="evt">
dijit.byId("stack").forward();
      </script>
  </button>

</body>
</html>